Valve are adding a new feature to Steam called 'Steam Greenlight' which will allow users to vote on which games they would like to see appear on Steam. Developers will be able to submit their games either in concept of playable form and then users can then vote on whether they would like to see it up for sale on Steam. Apparently there is no set watershed that the vote will need to reach, rather games will be published according to their relative interest compared to other games on Greenlight.

If you want to submit a game to Greenlight you will need a valid Steam account then you just fill out a form which requires one video, four screenshots a description and system requirements.

Greenlight will launch at the end of August.

Sounds like a pretty interesting system that could see some fun and unique games come to light.